Plate-clamp



April 1932- c. w. HARROLD 1,853,208

PLATEL CLAMP Filed July 26, 1950 avwemtoz CH/IALES ll HHRROLD Wm M Patented A 12, 1932 UNITED: rares- CHAR/LES w.) HABROLD, or, cn-EvELANn, onro, asszsuon ,r-o nannrssuynorn-rorrnn ooMr-AuY, OE'GLEVELAND, onto, A oonronarion or. DELAWARE PLATE-CHAMP Application 'filed' July 26,

My invention; relates toimproved clamping mechanism for securing: flexible sheets or platesuin even and firm contact with a suitable support;,.-such as a printing-press cylinder,,; and is particularlyadapted; for securing therubber-blankets aswell as the zinc plates to-the-cylindens in offsetl printing-presses, though'it may be advantageously used? in o her types of presses.

- The/objects of my invention are, among 'Qthenth-ings, toprovide asimple and novel clamp-mechanismifor such printing platesor blankets which shall beconvenient to operate and which; shallvstrai'n and: hold theplate vide a plate-clamping mechanism of such a character that a small opening or gap in the cylinder will alford sufficient space for its location and manipulation while periniiting an almost continuous printing surface on the cylinder by diminishing the width of the gap when the plate is in stretched printing position. A further feature of my invention is the provision of an improved plate-clamp embodying the desired attributes of simplicity, efficiency and durability, and which will enable the flexible blanket or plate not only to beclamped to the cylinders and easily and quickly loosened therefrom, but also to have the longitudinal clamping shafts supported at several points along the cylinder gap to produce a rigid, uniform and effective cla1np ing action with the adjusting mechanism'conveniently located outside the zone of such printing blankets and plates wrapped about the cylinders.

With these and other objects in View, my invention comprises the construction, combi- 1 nation and arrangement of the various parts hereinafter described, and thenparticularly pointed out in the appended claims.

In the accompanying drawings, Fig. 1 is a front elevation of the press cylinder with the flexible blanket or plate wrapped about derends 8' and 9, and also by having spaced;

139.9. Serial'No; 471,049.

the cylinder which is partlybroken away to show: my improved plate-clamp in its pre-: ferred for-m;

Fig.- 2 is anenlarged. detail view of. one .of the clamping shafts mounted in the cylinrder I Fig. Sis a; detail View on,- thelinea a of. Fig. 2;

Figt isan endview of the left. end: of the cylinder in Fig. 1 partly brokenaway an.d.:

5 is an, enlarged sectional view: on; the, line 5-5 of Fig; 1..

Similar numerals referto similanparts throughout the several figures.

Referring to the drawings, the: press Cyli': inder 6:is of the usual hollow construction, having. the peripheral. cylindrical. side-walls. 7 integral with the, ends 8 and 9 provided with. the. outwardly-extending bosses 10 and 11 which serve to support:the cylinder 61in the side-frames 12 and 13 0f the press.- (Figs Extendinglongitudinally along; the sur-, face of the cylinder Gris the cross-shapedslot. 14 (Fig. 5) having the oppositely disposedi rectangular recesses 15 and 16- enlarged. throughout the body of the cylinder 6 within: which recessesthe plate-clamping -mechanism. proper is-located,

The recesses 15 and 16 carry the longitudinal clamping shafts l7 and18 respectively having: their, cylindrical surfaces ridged, roughened or knurled at 19*as shown inzF'igs; 13,,l and part of their cylindrical surfaces is? cutaway at 20 and 21 (Fig, 5) between which; the ends of the flexible blanket on plate: are: inserted fiS'ShOWHLlIl Fig. 5-at thebeginning of; the plate-rclamping action; a

The shafts 17 and 1'8are-lrigidly'supported by having their ends journalled in the cylinapartbearings 2:2 cut away fronit-he. ridged or knurled surfaces 19 of the, shafts 17 and 18; The bearings 22 rotatably contact with the; supporting; ribs 23 (three shown foreach shaft 1 and 18 in F ig. 5) located in the recesses 15and 16which prevent the shafts 17 and 18, from-springingxapart when clamping theplate. The, outer ends of the shafts ,17 and; 18*aresquared (Fig. 4) to enable-the shafts to be turnediby acrank'orawrench,

Means are provided to hold firmly the shafts 17 and 18 in plate-clamping position that are best shown in Figs. 1 and 4: On the left end of Fig. 1 the shaft 17 carries the ratchet 24 adjacent the cylinder end 8 which is engaged by the pawl 25 pinned to the end 8; in like manner the shaft 18 (on the right of Fig. 1) carries the ratchet 26 which is enga ed by thepawl 27 pinned to the cylinder en( 9 also shown by dotted lines in Fig. 4).

I may also provide intermeshing gears 28 and 29 on the shafts 17 and 18, one of which is slidingly keyed to either of the ends of the shafts 17 and 18 (Fig. 4), so that one of the gears 28 and 29 may be slipped sidewise (shown by dotted lines in Fig. 1) out of mesh with its coacting gear in which case both ratchets 24 and 26 would be used to tighten the blanket or plate ends independently of the other. When the gears 28 and 29 are in mesh the tightening can be accomplished from either end of the cylinder 6 by rotating either shaft 17 or 18.

The rubber blanket or plate 30 having the ends 31 and 32 is wrapped about the cylinder 6 (Figs. 1 and with the ends 31 and 32 inserted in the slot 14 and in close contact with the cut-away surfaces and 21 of the shafts 17 and 18 respectively. As shown in Fig. 5 a thin metal strip 33 may be introduced between the blanket ends 31 and 32 to enable either end to be tightened independently of the other when the gears 28 and 29 are out of mesh since the interposed metal 2:; strip 33 will provide the necessary slippage between the opposed blanket ends 31 and 32.

In operation the shafts 17 and 18, after the ends 31 and 32 of the blanket or plate are in adjusting position as shown in Fig. 5, are revolved toward each other so that the ridged or knurled surfaces of the shafts will close on the ends 31 and 32 and bite into the fabric of the rubber blanket 30 along the line of con1- pression between the two shafts 17 and 18 which are rigidly and uniformly supported along their entire length by the spaced-apart bearings 22 revolving on the three-ribbed supports 23 thereby preventing the shafts 17 and 18 from springing apart. The ratchets 24 and 26 with their respective pawls 25 and 27 (with or without the intermeshing of the supports 23 thereby preventing the shafts 17 and 18 in tightened position.

This clamping action of the knurled shafts 17 and 18 may be applied to the flexible plates or rubber blankets of a printingpress, but is especially adapted to stretch and hold the rubber blanket on the press cylinder. My invention is not to be restricted to the precise details of construction shown since various changes and modifications may be made therein Without departing from the scope of the invention or sacrificing the advantages derived from its use.

I claim as my invention 1. A plate-clamp for holding a flexible plate on its support comprising oppositelydisposed coacting clamping shafts oppositely rotatable to grip and hold the plate ends interposed therebetween, each shaft being independently rotatable, detachable operative connections between the shafts to rotate same in unison, and separate means to lock each shaft in plate-holding position.

2. In combination, a printing cylinder having a gap, a pair of coacting clamping shafts recessed in the gap and rotatably supported upon spaced-apart bearings Within the gap, cut-away portions on the shafts between which the plate ends are interposed, the peripheral surfaces of the shafts being ridged or knurled to grip and hold the plate upon the rotation of the shafts in opposite directions, means for rotating said shafts in unison, separate means for rotating each shaft independently of the other, and means for locking each shaft in plate-holding position.

3. A plate-clamp for holding a flexible plate on its support comprising oppositely disposed coacting shafts oppositely rotatable to grip and hold the plate ends interposed therebetween, spaced-apart supports to bear on said shafts at a plurality of points, detachable operative connections between the shafts to rotate same in unison, and separate means for locking each shaft in plate-holding position.

CHARLES 1V. HARROLD. 

